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Abstract:

A method for ultrasonic testing includes placing an ultrasonic probe in a
liquid bath inside of a pressure vessel having an elastomeric diaphragm
stretched across an opening of the pressure vessel, applying pressure
within the pressure vessel to bring the elastomeric diaphragm towards a
test piece, and conducting ultrasonic testing of the test piece using the
ultrasonic probe. A device for ultrasonic testing of a test piece
includes a pressure vessel having an elastomeric diaphragm and an
ultrasonic probe disposed within the pressure vessel.

Claims:

1. A method for ultrasonic testing, comprising:placing an ultrasonic probe
in a liquid bath inside of a pressure vessel having an elastomeric
diaphragm stretched across an opening of the pressure vessel;applying
pressure within the pressure vessel to bring the elastomeric diaphragm
towards a test piece;conducting ultrasonic testing of the test piece
using the ultrasonic probe.

2. The method of claim 1 wherein the pressure vessel is a bell-jar.

3. The method of claim 1 wherein the test piece is a catalyst substrate.

4. The method of claim 1 wherein the test piece is a ceramic material.

5. The method of claim 1 wherein the step of applying pressure within the
container forces the elastomeric diaphragm against a surface of the test
piece thereby conforming the elastomeric diaphragm to the surface of the
test piece to provide intimate contact.

7. The method of claim 1 wherein the pressure is within the range of about
1 pound per square inch to about 15 pounds per square inch.

8. The method of claim 1 wherein the step of conducting ultrasonic testing
of the test piece using the ultrasonic probe comprises moving the probe
within the pressure vessel in a rotational or linear fashion.

9. The method of claim 1 further comprising positioning the test piece
proximate the elastomeric diaphragm.

10. The method of claim 9 wherein the step of positioning comprises using
a lift platform.

11. The method of claim 1 further comprising rejecting the test piece
based on the ultrasonic testing.

12. An apparatus for ultrasonic testing of a test piece, comprising:a
pressure vessel having an elastomeric diaphragm; andan ultrasonic probe
disposed within the pressure vessel.

13. The apparatus of claim 12 further comprising a liquid bath within the
pressure vessel.

14. The apparatus of claim 12 further comprising a drive shaft operatively
connected to the pressure vessel for moving the ultrasonic probe in a
rotational or linear fashion.

15. The apparatus of claim 14 further comprising a drive mechanism
operatively connected to the drive shaft.

16. The apparatus of claim 12 further comprising a pressure inlet to the
pressure vessel for increasing pressure within the pressure vessel.

17. The apparatus of claim 12 further comprising a lift platform for
lifting the test piece proximate the elastomeric diaphragm.

[0002]The present invention relates to ultrasonic testing. Ultrasonic
testing generally involves very short ultrasonic pulse-waves which are
launched into materials to detect internal flaws or to determine the
material type or characteristics of material. The nature of an ultrasound
test requires that the ultrasonic probe come into complete contact with
the surface of the test piece. The reason for this is that air between
the probe and the test piece will give inconsistent and incorrect results
in the test. Because the high frequency sound waves from the probe must
travel into the test piece consistently across the entire test area there
must not be any voids (air gaps) between the probe and the test piece.
The very nature of an ultrasound test is to find unwanted voids in the
test piece, without complete coupling between the test piece and the
probe the test is of no use.

[0003]There are two primary methods of ensuring that the coupling between
the probe 18 and the test piece are consistent. First, as shown in FIG.
1, coupling between the probe 18 and the piece 14 with a gel 16 and
significant down-force of 30-40 PSI may be used. Second, as shown in FIG.
2, the test piece 14 and probe 18 may be immersed in a liquid bath 20.
While both of these methods are very effective in many applications they
are not generally effective in high volume production, or with delicate
test pieces or parts that are non-immersible.

[0004]Other challenges arise when the test piece is large enough to
require that the probe be moved to test the entire surface. Because the
probe must remain in intimate contact with the surface of the test piece
motion of the probe across the surface of the test piece becomes very
difficult. The coupling mechanism (gel or elastomeric couplant) can be
worn out or will not maintain a consistent coupling with the test piece.
The combination of high down force and high friction makes moving the
probe while scanning ineffective. The probe can be moved over the test
piece in immersion applications (because it is not touching the piece)
however that is not of any use in non-immersion applications.

[0005]Due to problems such as the test pieces in question being fragile,
non-immersible and having non-uniform surfaces, ultrasonic testing has
significant limitation. What is needed is a way to overcome these and
other problems.

BRIEF SUMMARY OF THE INVENTION

[0006]Therefore, it is a primary object, feature, or advantage of the
present invention to improve over the state of the art.

[0007]It is a further object, feature, or advantage of the present
invention to provide for ultrasonic testing which does not require the
test piece to come in contact with liquids.

[0008]A still further object, feature, or advantage of the present
invention is to provide for ultrasonic testing which provides consistent
coupling with all irregular surfaces.

[0009]Another object, feature, or advantage of the present invention is to
provide for ultrasonic testing that does not require applying high
concentrated forces to delicate surfaces.

[0010]Yet another object, feature, or advantage of the present invention
is to provide for ultrasonic testing that allows the probe to be moved
over the surface with little effort while maintaining the coupling to the
test piece at all times.

[0011]One or more of these and/or other objects, features, or advantages
of the present invention will become apparent from the specification and
claims that follow.

[0012]According to one aspect of the present invention, a method for
ultrasonic testing is provided. The method includes placing an ultrasonic
probe in a liquid bath inside of a pressure vessel having an elastomeric
diaphragm stretched across an opening of the pressure vessel and applying
pressure within the pressure vessel to bring the elastomeric diagram
towards a test piece. Ultrasonic testing of the test piece is then
conducted using the ultrasonic probe. The pressure vessel may be a
bell-jar. The test piece may be a catalyst substrate.

[0013]According to another aspect of the present invention, an apparatus
for ultrasonic testing of a test piece is provided. The apparatus
includes a pressure vessel having an elastomeric diaphragm and an
ultrasonic probe disposed within the pressure vessel. There is a liquid
bath within the pressure vessel. There may be a drive shaft operatively
connected to the pressure vessel for rotating, translating, or otherwise
actuating movement of the ultrasonic probe. There may be a mechanism for
holding the ultrasonic probe in a static location.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 illustrates a prior art method of ultrasonic testing where a
gel couplet is used.

[0015]FIG. 2 illustrates a prior art method of ultrasonic testing where a
test piece is placed in an immersion tank.

[0016]FIG. 3 is a perspective view of an ultrasound bell jar assembly
according to one embodiment of the present invention.

[0017]FIG. 4 is a sectional perspective view of a portion of the
ultrasound bell jar assembly.

[0018]FIG. 5 is a sectional view of a portion of the ultrasound bell jar
assembly.

[0019]FIG. 6 is an exploded view of a bell-jar shown upside-down in
service mode.

[0020]FIG. 7 is an image showing no pressure in the bell-jar on the DPF
monolith substrate.

[0037]FIG. 24 is a perspective view of one embodiment of a drive assembly
bearing housing.

[0038]FIG. 25 is an exploded view of one embodiment of a drive assembly
bearing housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0039]The present invention includes a method for ultrasonic testing that
addresses problems with conventional ultrasonic testing. This invention
allows for the probe to be immersed while the part remains dry. An
ultrasonic probe is suspended in a liquid bath inside of a bell-jar with
an elastomeric diaphragm stretched across the bottom of the bell-jar. The
liquid on the probe side of the elastomeric diaphragm provides consistent
coupling with the test piece on the other side of the elastomer. By
applying pressure inside of the bell-jar the elastomer is forced down
against the test piece surface conforming to the irregularities in the
surface and providing intimate contact at all points. The liquid bath in
which the probe resides allows the probe to be moved effortlessly across
the surface of the part with no unwanted forces applied to the test piece
surface. Under very light pressure the elastomeric diaphragm only applies
a very slight pressure to the delicate face of the test piece while
maintaining the intimate contact required to ensure a consistent
ultrasonic test.

[0040]The following diagrams depict the invention as used to inspect for
internal cracking in automotive and diesel catalyst substrate. These
substrates are made of ceramic or silicon carbide and are susceptible to
internal cracking during manufacturing. The challenges in ultrasonically
testing these pieces are due to the fragile nature of the parts, their
inability to be immersed, their size and their typically irregular
surfaces. Test results from ultrasonic testing may be used to
characterize a test piece, identify flaws or defects in the test piece,
reject test pieces, identify the absence of flaws or defects in a test or
their other purposes. Of course, the present invention may be used in
other contexts for testing of other types of test pieces, especially
those which involve test pieces which are fragile in nature, have an
inability to be immersed, and have irregular surfaces.

[0041]FIG. 3 illustrates one embodiment of a bell-jar assembly applied to
an test object. The system 30 illustrates an ultrasound bell-jar assembly
32 proximate a test object 34. Here, the test object 34 is a catalyst
substrate. A substrate lift platform 36 is also shown for lifting the
substrate 34 to the ultrasound bell-jar assembly 32. The substrate lift
platform 36 allows non-identical test objects to be used in the same
setup. FIG. 3 shows the system with a part in testing. The bell-jar
assembly 32 houses the probe and sits above the test piece 34. The test
piece 34 is placed on a stable lift platform 36 which lifts it into the
diaphragm of the bell-jar assembly 32. Once the part is lifted into the
diaphragm, pressure is applied inside the bell jar to force the diaphragm
into the face of the test piece.

[0042]FIG. 4 illustrates another view of the ultrasound bell-jar assembly
32 where compressed air, which can be as low as one PSI, is received
through an inlet 38. A probe 40 within the ultrasound bell-jar assembly
32. The probe 40 is placed proximate or adjacent an elastomeric diaphragm
42. There is a liquid bath 44 within the ultrasound bell-jar assembly 32.
There is also a probe feed-through opening 46 to allow for electrical
connections to the probe 40 to be pass into the ultrasound bell-jar
assembly 32 while maintaining pressure. FIG. 5 illustrates that an
ultrasonic frequency signal 48 travels through the liquid bath 44 and the
pressurized diaphragm 42 and into the test piece 34. The probe 40 which
is located inside of the bell-jar assembly 32 is suspended in a bath of
liquid 44 which provides the consistent coupling with the top side of the
pressurized diaphragm 42. This liquid bath 44 allows the probe 40 to be
situated some distance from the diaphragm 42 and gives it the ability to
move freely over the surface of the part while maintaining its ultrasonic
coupling with the part. All connections to the probe 40 are fed through
the center shaft which supports and stabilizes the probe in the bath 44
via a sealed bearing assembly at the top of the bell-jar (probe
feed-through 46). Once the part is in place and the bell-jar is
pressurized the probe can sweep over the part to acquire the sample.
Other inputs into the bell-jar include fluid supply ports, pressure
relief ports, and additional ports for sensing and detection devices.

[0043]FIG. 6 provides an exploded view of the ultrasound bell-jar assembly
32. The assembly 32 includes a secondary backing ring 50 and a main
backing ring 52. A clamp ring 54 in conjunction with nuts 58 and bolts 56
is used to secure the diaphragm 42. Servicing the bell-jar and internal
components is accomplished by rotating the bell-jar upside-down and
removing the flange rings and the diaphragm. The backing rings 50, 52 are
placed to clamp the diaphragm 42 in place and to back the diaphragm 42 in
locations where the piece is not in contact with the diaphragm 42 to
eliminate bulging of the pressurized diaphragm 42 in unsupported regions.

[0044]FIG. 7 is a photograph of a bell jar test showing no pressure across
the face of the diaphragm. FIG. 8 is a photograph illustrating pressure
in pressure vessel on DPF monolith substrate-notice the cell structure
showing through the membrane surface. FIG. 9 is a photograph of pressure
in the pressure vessel on segmented substrate-notice the segments and
cell structure showing through the membrane surface. The pressure vessel
may contain a liquid or gel solution which will act in conjunction with
the pressurized diaphragm as the final couplant between the Ultrasonic
probe and the test piece. FIG. 10 is a photograph illustrating the test
pressure vessel with water under pressure.

[0045]FIG. 11 is a perspective view of one embodiment of an ultrasound
test unit. The ultrasound test unit 10 has a housing 12. FIG. 12 is a top
view of the ultrasound test unit 10. FIG. 13 is a front view of the
ultrasound test unit 10. FIG. 14 is a side view of the ultrasound test
unit 10.

[0046]FIG. 15 is a perspective view of one embodiment of a jar assembly
showing the drive assembly. The assembly 60 includes a drive shaft 62 and
a shaft collar 64. A hard stop level 66 is also shown. A motor mount
assembly 70 is shown as well as a bearing housing assembly 68. FIG. 16 is
a side view of one embodiment of jar assembly. FIG. 17 is a top view of
one embodiment of a jar assembly.

[0047]FIG. 18 is a sectional view of one embodiment of a jar assembly
taken along line A-A of FIG. 17. FIG. 19 is a detail view of A of FIG.
18. FIG. 20 is a detail view of B of FIG. 18. FIG. 21 is a detail view of
C of FIG. 18. FIG. 22 is a perspective view of one embodiment of a drive
assembly. FIG. 23 is a front view of the drive assembly of FIG. 22. FIG.
24 is a perspective view of one embodiment of a jar bearing housing.

[0048]FIG. 25 is an exploded view of one embodiment of a jar bearing
housing 80. A bearing housing 80 is shown as well as an outer bearing
spacer 82 and an inner bearing spacer 84. There is a lower bearing spacer
86. A thrust bearing 88 is shown as well as thrust washers 90. A shielded
ball bearing 92 is shown as well as round O-ring 94 and a second round
O-ring 96. A U-cup seal 98 is shown as well as a finger disk spring 100.

[0049]The present invention contemplates numerous variations, options, and
alternatives. For example, the jar assembly need not be a jar but may be
another form of a pressure vessel or container. The liquid bath may be of
any number of types of liquids. Any number of drive mechanisms may be
used. These and other variations, options, and alternatives are within
the spirit and scope of the invention.